The present invention relates generally to an indicating device for indicating the number of metered dosages that have been dispensed from, or remain in, an aerosol container, and in particular, to an indicating device adapted to be mounted to the aerosol container.
Aerosol dispensing devices have been developed that include a dose indicating device to indicate the number of metered doses that have been dispensed from the device, or to indicate the number of doses remaining therein. For example, patients have certain conditions that can be treated with medicaments dispensed in an aerosol and administered to the patient by inhalation. In one format, the aerosol with medicaments are contained in a container, and dispensed in metered, or measured, dosages with an inhalation device, or actuator boot. In such an arrangement, it can be important for the patient to be able to ascertain the number of metered doses remaining in the container, either by an indication of the number remaining therein or by knowledge of the number already dispensed therefrom, such that the patient is not caught unaware with an empty container when in need of the medicament. Thus, it may be important for the inhalation device to provide an accurate indication of either the number of doses remaining in the container, or the number of doses already dispensed therefrom.
Typically, a conventional aerosol container includes a body and a valve stem which can be depressed relative to the body so as to emit the metered dose of aerosol and medicament. The container typically is supplied with a predetermined number of metered doses, generally on the order of about 200, such that the counting of the number of valve stem depressions, and corresponding number of dispensed metered doses, can be directly correlated with the number of doses remaining in the container.
In operation, the container is typically received within a housing of the inhalation device, wherein the valve is brought into engagement with a support block in the housing. The user administers the medicament by moving the container relative to the housing so as to depress the valve stem and internal valve and thereby release a metered dose, which is typically administered to the user through a port or mouthpiece extending from the housing. After the dose is administered, the valve stem, which is typically spring loaded, biases the container away from the support block so as to again move the container relative to the housing. In this way, a metered dose of medicament is administered by each cycle of linear reciprocal movement of the container relative to the housing.
Some actuator boots, or other devices attached to the medicament container, have indicating devices that convert the linear reciprocal movement of the container relative to the housing into a one-way, or single-cycle, movement of an indicator, wherein the indicator identifies the relative fullness of the container, the number of metered doses remaining therein or the number of doses already administered. Although these actuator boots with indicators, or separate indicator devices, have provided the advantage of generally being able to keep track of the number of dosages, there remains room for improvement. For example, indicating devices of this nature may include complex moving parts which can be difficult to assemble and expensive to manufacture. Such devices may also be susceptible to counting inaccuracies due to the configuration of the indexing or mating parts, or require excessive amounts of space within the housing to accommodate the relatively large or numerous moving parts. Others still may impede or interfere with the airflow and medicament being dispensed from the inhalation device. Alternatively, some devices use electrical circuitry to count or record the dispersements. Such devices can be relatively expensive to manufacture, however, and typically require a power source which may be susceptible to damage in various environments, such as moist conditions.
Briefly stated, the invention is directed to an indicating device for indicating the number of metered doses that have been dispensed from or remain in a container. The container has a valve stem extending longitudinally therefrom; the valve stem being moveable between a closed position and an open position. The container dispenses a metered dosage when the valve stem is moved to the open position. The indicating device includes a base member adapted to be mounted to the container, a cap member moveably connected to the base member, an indicator member rotatably mounted to the cap member and a drive member adapted to rotate the indicator member an incremental amount upon a predetermined number of axial movements of the cap member relative to the base member.
In a preferred embodiment, the cap member is moveable relative to the base member along an axial path. The indicator member has a plurality of teeth and is rotatably mounted to the cap member about an axis substantially parallel to the axial movement of the cap member relative to the base member. A drive mechanism, including the drive member, comprises a ratchet wheel rotatably mounted to one of the base member and cap member about an axis substantially perpendicular to the axis defined by the axial movement of the cap member relative to the base member. The drive member is coaxially mounted with the ratchet wheel and a pawl is mounted to one of the cap member and base member. The pawl is selectively engaged with the ratchet wheel upon each axial movement of the cap member relative to the base member so as to rotate the ratchet wheel and drive member an incremental amount. The drive member is selectively engaged with at least one of the plurality of indicator member teeth upon a predetermined number of axial movements of the cap member relative to the base member such that the indicator member is rotated an incremental amount.
In another aspect, the indicating device comprises a first and second indicator member, with each of the first and second indicator members mounted to the cap member about an axis substantially parallel to the axial movement of the cap member relative to the base member. The first indicator member selectively engages the second indicator member as the first indicator member completes a usage cycle, representing one complete use of the indicating device and attached container, so as to rotate the second indicator member an incremental amount. In a preferred embodiment, the first indicator member comprises dosage indicia indicating the number of doses that have been dispensed from or remain in the container, while the second indicator member comprises usage indicia indicating the number of usage cycles that have been completed for the indicating device, or the number of usage cycles remaining therefor.
In yet another aspect, the indicating device comprises a first indicator mounted to the cap member about an axis substantially parallel to the axial movement of the cap member relative to the base member and a second indicator member mounted to one of the cap member and the base member about an axis substantially perpendicular to the axial movement of the cap member relative to the base member. In a preferred embodiment, both the first and second indicator members comprise dosage indicia indicating the number of doses that have been dispensed from or remain in the container, with the second indicator member rotating an incremental amount in response to each axial movement of the cap member relative to the base member and the second indicator member rotating an incremental amount upon a predetermined number of axial movements of the cap member relative to the base member.
In another aspect, the indicating device comprises a first and second indicator member mounted to the cap member about an axis substantially parallel to the axial movement of the cap member relative to the base member and a third indicator member mounted to the cap member about an axis substantially perpendicular to the axial movement of the cap member relative to the base member. In a preferred embodiment, the first and third indicator members comprise dosage indicia, while the second indicator member preferably comprises usage indicia.
In yet another aspect, the indicating device comprises a reset member connected to one of the drive member and indicator member. The reset member can be rotated to move the indicator member relative to the cap member independent of any axial movement of the cap member relative to the base member.
In another aspect of the invention, a method is provided for indicating the number of measured dosages dispensed from or remaining in the container. The method includes the steps of providing a housing for moveably supporting the container and providing an indicating device having a cap member, a base member and an indicator member rotatably mounted to the cap member. The method further comprises the steps of moving the cap member toward the base member so as to move the container along the longitudinal axis and thereby move the valve stem to the open position wherein a metered dosage is discharged, moving the cap member away from the base member, and moving the indicator member in response to the movement of the cap member relative to the base member.
Referring to a preferred embodiment, the method further includes the steps of engaging the ratchet wheel with the pawl upon one of the movements of the cap member toward and away from the base member and engaging the indicator member with the drive member so as to rotate the indicator member.
In yet another aspect, a method is provided for assembling a dispenser for dispensing metered dosages of medicaments from a container. The method includes the steps of providing a housing, disposing a container in the housing and mounting an indicating device to the container.
The present invention provides significant advantages over other aerosol dispensing devices and indicating devices used therewith. In particular, the indicating device can be separately manufactured and installed as needed on any number of conventional types of aerosol containers with little or no required modification to the container or housing. Moreover, the indicating device with its indicator member and drive mechanism is comprised of a relatively few, simple mechanical parts that are relatively easy to manufacture and assemble. In this way, the indicating device is made more robust and is less susceptible to damage when exposed to various adverse user environments. In addition, the drive mechanism and indicator member provide a reliable indicating device for indicating the number of doses dispensed from or remaining in the container, and the indicating device can be made in a relatively compact configuration that does not interfere with the use of the dispensing device.
The present invention, together with further objects and advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.